Method of preparing metal molds



l-1 w.24,1942.; w L RAPHAEL 2,303,092

METHOD OF PREPARING METAL MOLDS Filed Aug. 4, 1941 2 Sheets-Sheet 2 la02u/ @J2 f N yf www v azaa Patented Nov. 24, 1942 METHOD 0F PREPARINGMETAL MOLDS yWalter J. Raphael, Los Angeles, Calif., assignor ofone-half to Robert Neuschotz, Los Angeles,

Calif.

Appucation August 4, 1941, ser1a1N0.405,317

. 9 Claims.

This invention relates to a method of preparing metal molds used forproducing castings.

Heretofore metal molds have usually been produced by shaping the moldcavity in the sections of the mold by routing or milling out the` moldcavity in a block of metal that forms a part of the mold. Such procedureusually requires considerable labor of a highly skilled type and in`volves the expenditure of a great amount of time. Sometimes the block ofmetal from which the mold section is to be formed is cast to approximateshape and then finished by routing or milling out the mold cavity to thedesired formation.

An object of the present invention is to provide a new method forconstructing the sections of a l' metal mold whereby the parts of themold can be easily shaped to conform to the shape of the pattern or thecasting that is to be produced.

More specifically, an object of the invention is to provide a method ofpreparing metal molds wherein the mold sections are produced bysprayingmolten metal around a pattern so as to coat the pattern with metalconforming on its interior to the pattern shape. It has long beendesirable to be able to produce metal molds by spraying molten metalaround a pattern, but heretofore attempts made in this direction haveproven unsuccessful due to the fact that the sprayed-on metal eitherdoes not closely adhere to the pattern or it warps on cooling so thatthe mold sections do not accurately conform to the pattern shape becauseof YWarpage.

It is, therefore, another object of the invention to provide a methodYof producing metal molds by spraying molten metal over and around apattern Awherein the sprayed-on metal will be caused to .closely adhereto the pattern so as to 4accurately conform to the pattern shape andtive pattern being employed to produce a positivepattern half which isemployed in the construction of the mold in accordance with the presentprocess:

Fig. 3 is a sectional view illustrating the assembly of two positivepattern halves preparatory to the application of sprayed-on moltenmetal;

Fig. 4.is 4a sectional view illustrating the positive pattern halves ashaving been coated with metal applied thereto by spraying;

Fig. 5 is a partial view in vertical section illustrating the details ofthe construction of the fastening studs or inserts which are attached tothe positive pattern and which become parts of the mold sectionsproviding for their attachment to a suitable machineA for supporting themold sections;

Fig. 6 is a partial view in vertical section illustrating the manner inwhich the mold is divided or separated into its sections;

Fig. 7 is a partial view in vertical section illustrating a separatedlower portion of the mold;

Fig. 8 is a View in side elevation of the completed I nold, the sectionsof thel mold being illustrated in abutting relationship; A

Fig. 9 is a vertical section through a mold made in accordance with thepresent invention but illustrating the mold as having been slightlymodified-so as to receive a core;

Fig. 10 is a view in front elevation of a machine illustrating the moldmade in accordance withr the present invention as having been installed'tion of the machine illustrated in Fig. 10, the

positions capable of being assumed by the linkage connection beingillustrated in full andin dotted lines.

Referring to the accompanying drawings wherein similar referencecharacters designate similar parts throughout, I0 indicates an originalhalf of a pattern of the casting that is to be produced. This patternmay be of any desired configuration or shape and may be formed of wood,plaster, plastic, or other material conventionally employed for thispurpose. In accordance with conventional pattern making practices theoriginal pattern is divided usually into halves the upper half beingillustrated at IIJ and the bottom surface thereof being arranged on a.plane that is to be coincident with the parting plane or partingsurfaces of the mold.

The pattern l0 not only conforms to one-half or one portion of thefinished casting but preferably has 4formed thereon a pattern portion Ilthat is to provide the gate for the mold. If risers are to be present inthe mold riser patterns are also formed on the upper pattern half Il) ina similar manner to the gate pattern portion Il, The pattern section,the gates, and

-4 relationship asv illustrated in Fig. 3;

risers are au shaped with draft in the 'conventional manner.

The pattern I! is positioned on a spacer pattern I2 which may consist ofa flat plate or flat board or a plate whose surfaces' conform to theparting lineof the casting to `be made which preferably projectsoutwardly beyond all portions of.the pattern half III. The spacerpattern I2 rests upon'a suitable supporting suri' face or -table I3. Aflask I4 is positioned on the supporting surface I3 to surround thepattern half I and the spacer pattern I2. The pattern IU and spacerpattern I2 are coated with oil or stearic acid or other separatingmaterial and the flask is then filled with a self-hardening plasticmaterial I5 which may be a rubber producing a negative pattern I8 asillustratedin Fig. 2. The interior of this negative pattern is thencoated with oil, stearic acid, or other 25 'separating medium, and apositive pattern I'I is produced thereinby filling the cavity in thenegative pattern with a self-hardening plastic material which may or maynot be oi' the same character as that employed to make the negativepattern Il. The positive pattern I'I con forms in shape to the originalpattern half III except that there is integral Atherewith a spac' ingportion I8 equal in thickness and of the same size and shape as thespacing pattern I2.

In Figs. 1 and 2, I have illustrated .the construction of the positivepattern I1 ,correspond- -ing to the upper half ID of the original pat-ltern, it being understood that the upper halfof a the equivalent whichwill -resist deterioration the original pattern is usually that whichcarries with it the' gate or riser patternportions. v

portions of thefastening stud elements 20 and II. The lower half' oi'the original pattern, not

shown,`is likewise employed to make a negativeVA pattern correspondingto lnegative pattern .I8 f

.45 metal is applied thereto as indicated at 3l. This and from thisnegative pattern af positive pattern Il is-produced in a similar manner.

When these positive pattern halves are produced they are .assembledtogether in abutting Their spacer portions I8 are apertured at suitablelocations and fastening studs are applied thereto, the details of whichare illustrated in Fig. 5.

The fastening studs comprise male and female parts 20 and 2i,respectively, the male part a,sos,oaa

therethrough for the reception' of ejector, rods 3l, see Fig. 10. Withthe positive mold thus con'- structed as illustrated in Fig'. 3, thoseportions of the .mold that are to be coated with sprayed-. on metal arerst coated with a composition that will tendto cause the sprayed-onmetal to firmly adhere to the positive mold. I find that for thispurposeone such composition that may be emv ployed consists of one totwo parts of flowers of 1o sulphur and eighty parts of iron filings withsufficient water added to render the mixture a thin paste or paint that4can be brushed on to the surfaces of the positive pattern that are tobe i sprayed with molten metal. Another composition that may be employedconsists of ten parts of iron filings and three parts chloride of limelwith sufiicient water added to render the mix-f 'ture a .thin paste orpaint that can be brushed onto the positive pattern. In some instancesthe composition may be mixed with the plaster that forms the positivepattern, or if desired, the en-V tire positivepatternmay be cast of saidcomposition.

vIf the lpositive pattern is made of plaster of Paris it is'desirable tothoroughly dry the posis tive pattern following its production. This maybe dried in a baking oven or may be air dried if vsuiiicient time ispermissible for this method of drying. The application of the coatingwhich tends to cause the sprayed-on metal to adhere to the pattern maytake place before or after the drying of the pattern but if the coatingis applied after the drying of thev pattern it likewise should be driedbefore metal is sprayed onto the pattern. 'I'hose portions of thepattern that .are not to be coated with the sprayed-on metal are masked.In other words, the projecting portions ofthe ins/erts 29 may be maskedsuch as by cementing or tie' wiring on asbestos sheet or under thesprayed-on metal. The projecting 2I are similarlyv protected by masking.

With the pattern thus completed a coating of Yso as to completely coverthe lpositive patternl being applied to al1 exposed surfaces thereof andaround the inserts 29 and around the bases or roughened portions 28 ofthe fastening studs' 20 and 2I. When the coating of metal 3| is appliedentirely around the positive pattern 'it 20 having a pilot 22 receivablein a socket 23` 55 Will be fOllIld that any tendency 0f Wal'pge 0r inthe female part 2I. The pilot 22 extends through the apertures formed inthe projecting portions of the spacer portions I8 of the positivepattern halves and is internally threaded to receive a bolt 24 whichfastens the parts to'- gether and thus hold the positive pattern halvesin abutting relationship. The outer ends of the fastening studsare'internally threaded as at 25 to provide for attachment to verticallymovable mold section holders 26 and l2'I as illustrated'in Fig, 10. Eachfastening stud adjacent its inner end is externally roughened as at 28so that the for the coating to pull away from the positive pattern iseiectively eliminated. If.the external surface of the positive patternhas concavities I nd that the coating applied to the pattern tends tocause the sprayed-on metal toilrmly adhere .to the positive pattern evenin the concavities so that there is no tendency for the sprayed-on metalto shrink or retract from the concavities in the pattern. When thepositive pattern'sections have been completely coated with the sprayedonmetal the metal is then normalized to relieve all strains that may bedeveloped dur- -ing the spraying operation. This normalizing is usuallydone by heating the metal to approximately 1100 F. and then permittingit to slowly coolsuch as in a bed of lime.

When this step is completed the mold has the appearance as illustratedin Fig. 4, following which the edges of the mold surrounding the throughthe walls of the mold which forms holes spacer portions I8 are removedas illustrated in l desired in thebody portions of the mold sections`these may becut or drilled therein.

\ i a,sos,ooa

. tenminuneouny separate. wnen-the'opersnng Fig. 6. The removal of theseedge portions may be accomplished by grinding or cutting. If the metalhas been applied over thel gate or riser portions li of the positivepattern-this metal is also removed so as to open the entrances to the lgates and risers. Thus, by the removal of the edge portions the mold isdivided into upper and lower sections constituting the cope and the dragof the mold. They may then be separated from eachother and the positivepattern removed therefrom. Those portions of the mold sections that wereformed by the spacer portions I8 provide the parting surfaces of themold sections 'and when the mold sections are assembled together inabutting relationship as illustrated in Fig. 8, the cavities in the moldsections will lthen each accurately conform to the halves of theoriginal pattern. If it is desired to vent the mold, small grooves maybe cut or ground in the parting surfaces as illustrated at' 32, and ifvent holes are The thickness oi' the metal coating S may vary. However,for .ordinary purposes this need not exceed one-quarter or three-eighthsinch.- The metal used for the coating may likewise vary depending uponthe nature of the material Vthat is to -be cast. .For example, if thecasting is to be of aluminum. the initial spraying of the positivepattern maybe performed with a chromium steel .alloy and the balance ofthe coating 3| may be formed of low cost. low carbonv steel so that thechromium steel alloy which forms `a facing on the interior of the moldcavity will edectively re-v sist any pitting eil'ect lof the moltenaluminum.

T he `coating 3l need not be formed. however, of a.

ferrous material. Bronze or other metals may be substitutedl therefor-if desired, depending upon the nature of the material .that is to formthe casting. 1

In the event that the casting .that is-tobe produced is to be cored, thepattern i is equipped divided into two parts 'but patterns divided intoadditional parts maybe used if desired. The na .ture ofthe mold andpattern. to some extent will link I2 is inthe vertical 'position or fullline posi tion themold sections are brought into 'abutting relationshipin which position the molten material that is to be cast-'may be pouredinto the mold through the gate.- The ends of theejector rods "which areexposed on the interior of the mold chill the casting in' the localitiesof their' ends, and when the mold sections are separated" they slideupwardly and downwardly respectively on these ejector rods so that whenthe molten material has been poured into the mold to form the castingand the mold sections are separated -the ejector rods serve to supportthe casting between the separated mold sections; Thereafter,

set in ahorizontal plane. This type of machine is edaptedto be usedthereon, moms having para l ing planes and gates or risers in a verticalplane 'rather than in the horizontal plane illustrated.

It v'will -also be understood that in making the .mold in accordancewith .the present .invention j v that 'it is not restricted to the useof patterns..

affect the type of machine used, that is whether the mold will bemounted on a machine which separates the mold vertically as shown, orhori4 zontally. f-

While itis advantageous to employ a coating on the positive pattern tocause the sprayed-oni- 'metal to adhere `to the surfaces of the patternwith core prints which define portions vof the mold indicated at 33 toYreceive portionsof the core illustrated at 3l so that the core whichmay be a sand core or heat resistant plaster, is properly supportedwithin 'the closed mold. Where the shape of the core permits, metalcores may be used in the conventional way. j

' With the mold thus completed it may be mounted within any suitableholder or a casting.

- machine such as that illustrated in Fig. 10,

whereinthe lower moldsection is fastened by means of its fastening studsto the lower holder 21 and the upper mold section is fastened' by thosefastening studsto the upper vholder 26. These holders are movable towardand away from each other upon suitable vertical guides 35: Elector rods30 are suitably mounted on supports 36 and 31 and extend into theopenings in the mold walls formed by the inserts 29, or holes which mayhave been drilled for the purpose. Thev lower ejector support 3l isvertically movable by means of links 'which connect it to an eccentricshaft 38. The upper mold support V2li is connected by means of links 39and 40 to thetop of the machine. Links 4l connect the pivotal connectionbetween links 3S and 40 to an operating link 42. Similarly, the lowermold support is connected by means of links 43 and M to the bottom ofthe machine and links 45 connect the pivotal connection between theselinks to the operating link I2.

As illustrated in Fig. 11, when the opera-ting link the pattern. I dndthat if the lis not applied entirely -around the pattern the warpage ofthe metal on cooling' brings about distortion so that-the m'olddoes notconform to-the'f,v pattern. In some instances. the sprayed-'on need .notcompletely Isux'rotuid the pro' vided that. it sufficiently" overlaps'an exposed l "side, but under these circumstances ofcomposition'previousl! unna-:munitie: accuses',tofirmlyadheretothe-padtivepat in some instances this coating may beomitted, i particularly where the is. small, provided. that thesprayed-on metal completely surrounds sprayed-on metal ment of thecoating referred to ishishly the metal tern.'

-While itis possible.to?dispense''vritlifn'lak'ing a negativev patternyand a Apositive pattern therefrom, and instead use the original pattern.is and the spacer-pattern-l l2 in place of the positive pattern I1,Iprei'er positive patterns so that if difilcnlty' is experienced inremoving *the positive pattern from the completed mold the originalpattern is in no way.

defaced or mutilated- In some instances the ,to make the negative andmaking of the original pattern and 'theproduction of a negative patterntherefrom. can vbe dispensed with. The negative pattern may be made asthe original pattern and a positive pattern or print may be obtaineddirectly therefrom. It is also possible to make the positive patternsections not integral with the spacer I l. Thus positive patternsections can be produced conforming in shape to the original patternsections and thesapattern sections may then be cemented, to s aepjaratespacer with silicate of soda or thelik'e. I. -f it will tbe,.-

. .From the above-described appreciated that s'novel, simple; andadvantage."

l2 is swung from the full line position to the eusmenwd er preparimem/meuh nu provided which of' routing or milling out the shape of thecasting in the mold. Molds produced in this manner can be caused toaccurately conform in shape to that of the original pattern I0.

Various changes may be made in the details of construction withoutdeparting from the spirit or scope of the invention as dened by theappended claims.

I claim:

1. The method of making metal molds having partingskt'vhicii includesapplying pattern sections to the sides of spacer patterns, which sidesare to define parting surfaces of the mold, forming negative patternsfrom the pattern sections and spacer patterns producing positivepatterns from the negative patterns, positioning the positive patternsin opposition with their spacer portions disposed together, coating thepositive patterns with metal, dividing the mold around the spacerportion, and removing the metal that projects beyond the partingsurfaces of the mold sections defined by the spacer portions. I

2. The method of making molds which includes incorporating in thesurfaces of positive pattern sections a material containing metalfilings which will cause sprayed-on metal to firmly adhere to thesurfaces of said sections, and spraying the sections with molten metal.

3. The method of making molds which includes incorporating in thesurfaces of positive pattern sections a material containing metalfilings which will cause sprayed-on metal to firmly adhere to thesurfaces of said sections, assembling said sections in spacedrelationship, spraying metal over the sections and over the interveningspace therebetween, and removing the metal between the pattern sections.

4. The method of making molds which includes incorporating in thesurfaces of positive pattern sections a material containing metalfilings which will cause sprayed-on metal to firmly adhere tov thesurfaces of said sections, assembling said sections in spacedrelationship, spraying metal over the sections and over the interveningspace therebetween, normalizing the sprayed-on metal, and removing themetal between the pattern sections.

5. The method of making molds which includes assembling in spacedrelationship positive pattern sections on which metal may be sprayed,ap-

plying to said sections holding or supporting inserts, maskingprotruding portions of the supporting inserts, and spraying metal overthe positive pattern sections and across the space therebetween, andfinally removing the metal between the pattern sections leaving exposedportions of the inserts embedded in the sprayed-on metal.

6. The method of making molds which includes applying to the surfaces ofpositive pattern sections a material containing iron filings which willcause sprayed-on metal to firmly adhere to the surfaces of saidsections, and spraying the sections with molten metal.

'7. The method of making molds which includes applying to the surfacesof positive pattern sections a material composed mainly of iron filingsand a small amount of fiowers of sulphur to cause sprayed-on metal tofirmly adhere to the surfaces of said sections, and spraying thesections with molten metal.

8. The method of making molds which includes applying to the surfaces ofpattern sections amaterial composed mainly of iron filings and a smallamount of chloride of lime which will cause sprayed-on metal to firmlyadhere to the surfaces of said sections, and spraying the sections with-molten metal.

9. The method of making molds which includes incorporating in thematerial from which a pattern is made iron filings so that the ironfilings on the surface of the pattern will cause sprayedon metal tofirmly adhere to the surfaces of the pattern, and spraying the sectionswith molten metal.

WALTER J. RAPHAEL.

